The patriarch of a three-generation family Diamond District business is suing one of his​ two​ sons for $2 million, claiming the wayward child impersonated him and his brother to steal clients, suppliers, jewels, and cash then opened a competing business on the same W. 47th Street block.

Richard Friedman inherited the nearly 100-year-old business I. Friedman & Son Jewelers from his father​,​ Irving​,​ in the 1970s, according to the Manhattan civil suit.

His sons​,​ Robert and Corey Friedman​,​ joined the business in the 1990s and signed a shareholder agreement that dictated their salaries and included a non-complete clause, the suit says.

But when an employee left the company in June she enticed Corey to join her, according to court papers.

That’s when the ungrateful son “intercepted calls and email directed to Richard or Robert from prospective customers, pretended he was Richard or Robert and diverted that business” to the new operation, Corey Friedman Fine Jewelry, the suit says.

Corey “decided to simply steal resources from I. Friedman in an effort to place itself in a position to compete,” the suit says.

Corey’s shop is located at 50 W. 47th St., just 350 feet away from the original family business at 10 W. 47th St.

Reached by phone Corey claimed, “I know nothing about” the lawsuit.

When asked why he left the family business he added, “I have no idea what you’re talking about,” and hung up.

Richard is suing to put his son out of business and for $2 million to compensate for lost profits, damage to his reputation and “customer confusion.”

He did not immediately return a call. His attorney declined to comment.